Elevator control system



Aug. 23, 1938. H. w. WILLIAMS 2,128,063

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ZDKMMA AAA WITNESSES: INVENTOR ATT EY Patented Aug. 23, 1938 UNITED STATES PATENT. OFFICE ELEVATOR CONTROL SYSTEM Application December 9, 1936, Serial No. 114,960 g 39 Claims.

The present invention relates to systems of control for electric elevators and more particularly to such systems in which a number of elevator cars operating together as a bank are controlled by passenger-operated push buttons located at the various floor landings.

Many systems have been developed in which push buttons located at the various floors of the building are effective to cause the stopping of one or more elevator cars which serve the corresponding floors. In certain of these systems, the push buttons at the floor landings are associated with all of the cars of the bank and cause the stopping of a selected one of such cars upon its approach to the corresponding floor, travelling in the corresponding direction. In others, push buttons individual to each car are located at the floor landings, and operation of any button is effective to stop only the corresponding car, as disclosed in the patent of Edgar M. Bouton and William F. Eames, No. 2,066,906, assigned to the Westinghouse Electric Elevator Company.

The systems in which the push buttons are common to all of the cars have been alternatively arranged so that operation of the button registers a call which is available to any of the cars of the bank, but which is not appropriated to any particular car until one of the cars approaches within a certain distance of the corresponding floor; or so that operation of any button registers a call which is immediately appropriated to a particular car, usually the car which is nearest the corresponding car at the time the call is registered.

In the operation of each of the systems mentioned above, there is a tendency for the several elevator cars to distribute the building traffic unevenly, and, in the taller buildings, for the cars to become bunched and thus disrupt the intended spacing between the cars.

These systems also tend to provide better service at certain floors than at others, particularly during the noon and evening rush periods, at which times a relatively large number of calls are registered at practically all floors of the building within a relatively short period of time. At such rush periods, each elevator is filled to capacity by a relatively few stops, perhaps three or four. Each car is usually required to make these few stops at the upper floors and so passes the lower floors without stopping. Because of the frequency with which calls are registered, it has been found that the next car of the series is also filled to capacity by three or four stops at upper floors and so passes the lower floors without stopping. In the operation of these systems, therefore, the response to calls registered from lower floors of the building is delayed until most of the tramc from the upper floors has received attention.

In order to provide more uniform service throughout the building during heavy traffic peaks, the quota system, as disclosed in the patents of Richard F. Jones, No. 2,104,522, and of William F. Eames, No. 2,014,478, both assigned to Westinghouse Electric & Manufacturing Company, has been devised. In accordance with the quota principle, each car is normally assigned a Zone of floors extending in advance of itself up to the next car travelling in the same direction, or if no car is in advance of it travelling in the same direction, up to the last car travelling in the opposite directions. All corridor calls for service in the corresponding direction of travel registered at floors included in a cars zone are assigned to the car as soon as registered, until a predetermined number or quota of calls is received. Upon receipt of its quota of calls, the car loses its Zone and cannot accept any further calls until it reaches a terminal. The zone of a car which has accepted its quota of calls is transferred to the next following car, so that the zone of the latter extends from its own position, past the car having its quota, up to the next succeeding car travelling in the same direction.

It has been found in practice that the quota system distributes the acceptance of calls between upper and lower floors satisfactorily during heavy trafiic conditions, and this system provides a more uniform time interval between the operation of a push button and the stopping of a car in response thereto, throughout the entire range of floors served by the system. Because of this more uniform time interval, the percentage of stops which result in the picking up of a single passenger is decreased; the average number of passengers picked up per stop is increased;

the average number of stops per trip is decreased; and the average number of trips for the system as a whole per unit time is increased, as compared to corresponding values for systems otherwise similar but lacking the quota feature. However, in the quota systems of the prior art, such as disclosed in the Jones and Eames patents mentioned above, as in other systems employing zoning of the hatchway, a car may overtake an earlier dispatched car and gain a distance of several floors in advance of it. In such a case, the floors between the overtaking car and the one passed are transferred to the zone of the latter, and any accepted calls at these floors tend to retard the delayed car still further and to lengthen its zone. At times, therefore, the cars may arrive at a terminal in a difierent sequence from that in which they were dispatched from other terminals.

The present invention relates to quota systems, and has for one object the control of the system in such manner that, when one car overtakes another, the burden of answering floor calls is imposed more heavily on the overtaking car rather than the car being overtaken, so as to tend to equalize the trip time of the two cars.

Another object of my invention is to provide an elevator system of the type indicated above, in which part or all of the calls assigned to a car are transferred to a later-dispatched car which overtakes it.

A further object of my invention is to provide an elevator system of the type indicated, in which floor lantern transfers are made at the time a car stops, in the event that the car is stopping in response to a call previously assigned to a different car.

Another object of my invention is to provide a novel elevator system in which floor calls are assigned to a definite car as soon as registered, but are appropriated by another car in the event that the latter arrives at the calling floor in the proper direction to answer the call, before the car to which the call was initially assigned arrives.

Another object of my invention is to provide a novel elevator system operating upon the quota principle which will include means for transferring the zone of an overtaken car to the car overtaking it.

It is a further object of my invention to provide a novel elevator system operating upon the quota principle, wherein, in the event that a car is overtaken by another one, the overtaken car answers the calls already assigned to it but no others.

A further object of my invention is to provide a novel elevator system in which common stopping apparatus for a plurality of cars is provided, this stopping apparatus being efiective to stop the first car in condition to receive passengers which arrive at a calling floor, but the system being such that a car having more than a predetermined number of calls assigned thereto is disconnected from the common stopping apparatus.

A further object of my invention is to provide a novel elevator system of the quota type, in which calls are assigned to the cars as soon as received in accordance with zones of floors determined by the positions of the cars, and in which common stopping apparatus is provided for stopping any car which arrives first at a floor at which a call is registered.

Other objects of my invention will become evident from the following detailed description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a diagrammatic view of certain mechanical elements which may be used in the practice of my invention,

Figs. 2, 3, 4, 5 and 6 are diagrammatic views, which together illustrate a complete control systern for two cars, arranged in accordance with the present invention. These figures may be conveniently placed one above the other, in the order mentioned, with Fig. 2 at the top,

Figs. '7 and 8 are key diagrams showing the relative positions of relay coils and contacts on Figs. 2 and 3, respectively. In Figs. '7 and 8, all coils and contact members are given the same horizontal positions on the sheets as the corresponding contacts on Figs. 2 and 3, respectively,

Figs. 9 and 10 together constitute a key diagram for the coils and contacts of Fig. 4,

Figs. 11 and 12 together constitute a key diagram showing the relative positions of coils and contacts of Fig. 5, and

Figs. 13 and 14 together constitute a key diagram for the coils and contacts of Fig. 6.

Throughout the figures, the various reference characters serve as a guide to the relation between coils and contacts. For example, coil IUR. operated contacts iURl, IURZ, IUR3, etc.

Except where otherwise specified, in the following description, each of the relays or switches shown in the drawings, is of the usual electromagnetically operated type, comprising an operating electromagnet and a cooperating contactcarrying armature. Throughout the drawings, the contact members are shown in the position occupied thereby when the corresponding switch is in the deenergized condition. Contacts open under these conditions are illustrated by two short and slightly spaced semi-circular segments, and contacts closed under these conditions are illustrated by a small circular element having a short straight line drawn through the center.

Description of apparatus The system illustrated in the drawings is arranged for controlling two cars A and B. The control systems individual to the two cars are identical and corresponding elements in each are given similar reference characters, except that for car B, each reference character is given a prefix B.

The control systems illustrated for the respective cars are of the type in which the car is started by means of a manually operable switch on the car and thereafter continues in operation until a stop is initiated in response to a hall button. In a practical embodiment of the invention, car buttons would also be used to initiate stops of the individual cars, but for simplicity such buttons and their associated circuits have been omitted from the drawings. The particular motor control system employed is not a novel part of the present invention, but has been illustrated, in Fig. 2, as being of the variable voltage or Ward-Leonard type, utilizing inductor switches to initiate the slow-down and stopping operations.

Referring to the left-hand half of Fig. 2, the

control system for car A comprises a motor ID,

the armature of which is connected in series with the armature of a generator I I. Motor ID is provided with a field winding l2, which for purposes of description, has been illustrated as directly connected across two line conductors LI and L2.

Ill)

Generator H is provided with a separately excited field winding 13, the polarity and degree of excitation of which may be selectively controlled by means of up and down reversing switches U and D, and a speed switch V, to thereby control the direction and speed of motor Hi. Tne usual electromagnetically released, spring applied brake I4 is associated with motor ill.

The system preferably embodies some form of speed regulating mechanism to render the operating speed of motor H) substantially independent of the load on the elevator car, and this mechanism, for convenience, has been illustrated as comprising a cumulative series field winding l5 associated with generator H.

The reversing switches U and D and the speed switch V are controlled in starting by means of a master switch MS, carried by the car, as shown in Fig. l, and having up contacts MSU and down contacts MSD. The reversing switches U and D and the speed switch V are controlled during slow-down and stopping by means of a slow-down inductor switch E and a stopping inductor switch F, both of which are carried upon the elevator car.

Each elevator car A and B is provided with a suitable floor selector, which, for simplicity, is shown in Fig. 1 as of the screw-driven mechanical type. The fioor selector 29 for car A comprises a stationary panel iii, to which are attached a row of up segments and a row of down segments. The up row includes one segment for each intermediate floor and the upper terminal floor designated respectively 2a, 3a, 4a and 5a, and an auxiliary segment la for the lower terminal floor. The down row includes one segment for each intermediate floor and the lower terminal floor, designated lb, 22), 3b and 4b, and an auxiliary segment 5b for the upper terminal floor. Floor selector 20 also comprises a screw-driven cross-head 22, which carries brushes a and b for cooperation with the up and down rows of segments, respectively. The cross-head 22 is reciprocated by screw 23 and is also mounted for a limited amount of rotation with it. With this latter arrangement, during upward travel of the car, the cross-head brush a engages its associated up segments but brush 2) does not engage its associated down segments, and, during downward movement, brush 1) engages its associated down segments, and brush a does not engage its associated up segments. Brushes a and b are preferably spring mounted, so that, upon a reversal of direction, a segment in the row, corresponding to the reverse direction of travel is engaged just before a segment in the other row is disengaged. Shaft 24 and a suitable reducing gear unit 25 are arranged to rotate screw 23 in response to movement of the elevator car.

The spacing of the segments is such that a brush engages a segment for a particular floor just after the car leaves the preceding floor, and remains in engagement therewith until the car has moved a similar distance past the particular floor. The brush dimensions are such that a segment for one floor is engaged just after the segment for a preceding floor is disengaged, there being a transition interval, during the period of travel of the brush from one segment to the next, when neither segment is engaged.

The inductor switches E and F, mentioned above, are preferably of the type disclosed in Patent No. 1,902,602, granted March 21, 1933, to Williams, et a1. and assigned to the Westinghouse vElectric Elevator Company. As there, described,

and as shown diagrammatically in Fig.1, each inductor switch comprises an electromagnet and two contact-carrying armatures disposed in the magnetic circuit thereof. The arrangement of the switch is such that energization of the electromagnet has no immediate effect upon the positions of the associated armatures. 'When, however, the switch is moved into the region of a magnetizable plate associated with either armature, that armature moves to a contact-opening position. Preferably also, the armature remains in the contact-opening position, after having been initially moved thereto, as long as the electromagnet remains energized, even though the switch is moved out of the region of the magnetizable plate.

Inductor switch E is provided with an up contact armature El and a down contact armature E2, and inductor switch F is provided with corresponding up and down armatures F1 and F2. An inductor plate UE (see Fig. 1) for each intermediate floor and the upper terminal floor is associated with armature El, and a corresponding inductor plate DE, individual to each intermediate floor and the lower terminal floor, is associated with armature E2. An inductor plate UF for each intermediate floor and the upper terminal floor is associated with armature Fl, and an inductor plate DF for each intermediate floor and the lower terminal floor is associated with armature F2. A single complete set of such plates, for the second floor, is illustrated in Fig. 1.

The inductor plates associated with switch E are located in the hatchway in such position as to cause an operation of the corresponding armature when the car reaches the slow-down points for the respective floors, travelling in the corresponding direction, and the plates associated with switch F are located in the hatchway in such positions as to cause an operation of the corresponding armature just before the car reaches the respective floors, travelling in the corresponding direction.

Referring again to Fig. 2, the coils of inductor switches E and F are arranged to be controlled by means of a stopping relay H, a holding relay G, and an auxiliary control relay M. Relay H, in turn, is arranged to be selectively operated as the car approaches floors for which the calls are registered in response to contacts 4URI, etc., of

the floor relays, later described. Contacts lUPI, 3DPl, etc., on a series of car position relays, later described, together with the contacts IURI, etc., of the floor relays, commutate the operating circuits for relay H, as the car approaches the several floors, travelling upwardly or downwardly.

An auxiliary stopping relay EC is also provided for initiating stops for car A in the event that the latter is dispatched later than car B and thereafter overtakes car B, disturbing the dispatching sequence. This condition will be more fully discussed in connection with the operation of the system.

Referring to Fig. 3, the bank of elevators comprising cars A and B is provided with a common up floor relay for each intermediate floor and the lower terminal floor, and with a common down floor relay for each intermediate floor and the upper terminal floor. an operating coil and a resetting coil. The relay armature is arranged to move to the actuated position upon energization of the operating coil and to resume the deenergized position upon energization of the resetting coil, which acts to Each floor relay comprises magnetically oppose the effect of the operating coil.

The drawings illustrate a system arranged for three intermediate floors, and upper and lower terminal floors, and the up floor relay operating coils are designated IUC, ZUC, 3UC and AUC. The down floor relay operating coils are designated 2DC, 3DC, 4DC and 5DC. The resetting coils for these floor relays are shown immediately below the corresponding operating coils and have the same reference characters with the sufiix N.

As shown in Fig. 3, the floor relays IUC etc., are connected for actuation by push buttons corresponding to the various floor landings, the up floor buttons being designated IU, 2U, 3U and 4U, and the down floor buttons being designated 2D, 3D, 4D and 5D.

Referring to Fig. 4, the upper part of the figure shows a plurality of call storing relays, of which a set for both up and down directions is provided for each car. The up direction call storing relays for car A are designated IUR, ZUR, 3UR and 4UR, and the down direction call-storing relays for the same car are designated ZDR, 3DR, 4DR and 5DR. The corresponding callstoring relays for car B are denoted by the same reference characters with the prefix B added. The call storing relays IUR, 2UR etc., are operated to select the car A or B which will accept a given hall call, dependent upon which car has the zone which includes the calling floor. Upon operation of any floor relay IUC, ZUC, etc., of Fig. 3, one of the call storing relays lUR or BIUR etc., of Fig. 4 immediately closes and stores the call until answered. The call storing re-- lays IUR, ZUR, etc., also control the floor la11-- terns at the various floors so as to provide in stant signals as soon as a button is pushed. This operation, together with other operations performed by the call-storing relays IUR, ZUR, etc., will be explained in more detail in connection with the operation of the system as a whole.

The lower part of Fig. 4 shows the circuits of the car position relays, car A being provided with an up car position relay for each intermediate floor and the lower terminal floor, designated IUP, 2UP, etc., and a down car position relay for each intermediate floor and the upper terminal floor, designated 2DP, 3DP, etc. Car B is provided with similar relays, denoted by corresponding reference characters preceded by the prefix B.

The car position relays IUP, 2UP etc., for each car are caused to respond directly to the position of the associated car by means of contact segments Ia, 2a, 3a, etc., and movable brushes a. and b of the floor selectors 20 and 1320, described above in connection with Fig. 1.

The upper part of Fig. 5 shows a series of common zoning relays, of which there is one up relay for each intermediate floor and the lower terminal floor, and a down relay for each intermediate floor and the upper terminal door. The

up zoning relays are designated lUX, ZUX, 3UX

and 4UX, and the down zoning relays are designated 2DX, 3DX, 4DX and 5DX. The common zoning relays respond directly to the positions of the respective cars of the bank, as illustrated by the parallel connected contacts of car position relays IUP and BIUP; 2UP and BZUP, etc., of both cars A and B in the circuits thereof.

The zoning relays IUX, 2DX etc., control the zoning circuits of the call storing relays IUR, 2DR etc., (Fig. 5), are retarded in dropping out,

by any suitable means, so that their contacts remain closed during the short time interval after one position relay such as IUP opens, before the next succeeding position relay 2UP closes. For this purpose, the zoning relays lUX, ZDX etc., may be provided with a short-circuited turn, as indicated diagrammatically in Fig. 12.

Referring further to Fig. 5, the car selecting relays S and BS, near the middle of the diagram, are provided to supplement the action of the common zoning relays under conditions where two or more cars are standing at the same floor. Relays S and BS respond directly to the positions of the corresponding cars, through contacts 5DP5, 4DP5, etc., associated with the car position relays. Both relays S and BS are connected in parallel relationship to a plurality of selective resistors SSRD, 4SRU, etc. The arrangement is such that the selecting relays S and BS normally are energized, but are momentarily deenergized as the car passes transfer points between floors. The resistance values of the selective resistors ESRD etc., are such that if two or more selecting relay circuits corresponding as to floor, are simultaneously completed, none of the selecting relays operate, or if one or more additional selecting relay circuits are completed corresponding to a floor for which selecting relay circuit is already complete, such additional selecting relays do not operate. The selecting relay associated with the already complete circuit remains in the operated position, however. A manually operable dispatchers button PB and BPB is associated with each selecting relay S and BS, respectively, for operation in the event that two or more cars are standing at the same landing with none 01" the selecting relays in operated condition. Operation of a dispatchers button short-circuits a corresponding section of resistance PBR or BPBR, respectively, and causes operation of the selecting relay for that car.

As also shown in Fig. 5, near the bottom thereof, each car of the bank is provided with a set of floor lanterns individual to it, there being an up floor lantern for each of the intermediate floors, and the lower terminal floor, and a down floor lantern for each of the intermediate floors and the upper terminal floor. The floor lanterns for car A are designated IUL, ZDL, etc., and the lanterns for car B are similarly designated but have a prefix B. Each floor lantern is arranged to be illuminated through either of two circuits, one of which is controlled by a corresponding call-storing relay contact, such as 5DR3, for the same floor, and the other of which is arranged to be controlled by a car position relay contact, such as 5DP1, for the same floor. a contact S3 of the selecting relay S and a contact M3 of the auxiliary control relay M. The former circuit causes the lighting of a floor lantern to occur as soon as a particular floor call is appropriated to one of the cars. The latter circuit causes a floor lantern to light at the time the car stops at the corresponding floor, in response, for example, to a call previously assigned to the other car.

Referring to Fig. 6, each car is provided with a quota relay Q and EQ, respectively, which serves to remove the car from the zoning system and prevent the acceptance of further calls thereby, under either of two conditions. The first of these conditions is that the weighted total of calls assigned to the car equals a predetermined number, termed the cars quota. It has been found in practice that at certain floors of a building, more passengers usually enter a car during each stop, than at other floors. Floors at which the larger number of passengers enter may, therefore, be given a greater weight in determining the quota number than other floors at which a smaller number of passengers commonly enter a stopped car. For example, if approximately double the average number of prospective passengers enter a car stopped at the fourth floor, the latter floor may be given a weight of 2 as compared with other floors. If the cars quota is 3 stops, therefore, it may stop at any three floors except the fourth without filling its quota. How-- ever, if it stops at the fourth floor first,v it may stop at only one other floor to fill its quota. The manner in which the various floors are weighted will be explained in connection with the totalizing relays T and ET.

The second condition which will cause opera tion of a quota relay Q or BQ is that the corresponding car has been overtaken by another car, travelling in the same direction.

The quota relays Q and BQ are each provided with holding circuits controlled by limit switches LS and BLS, respectively, controlled by suitable cams (not shown) so as to drop out the corresponding quota relay at the upper and lower limits of travel of the corresponding car.

A series of selectivity relays IUK, ZUK, 3UK and AUK, common to both cars, is provided for the up direction of travel, and a similar series ZDK, 3DK, lDK and SDK is provided for the down direction of travel. The selectivity relays lUK, etc., are controlled by parallel contacts of the call storing relays IUR, BIUR, etc., so as to operate in response to the operation of any call storing relay for the corresponding floor. The selectivity relays IUK, ZUK, etc., serve to prevent the energization of any deenergized call storing relays IUR, ZUR, etc., (Fig. 4), for any floor and direction of travel, when another call storing relay for the same floor and direction of travel is already energized.

The circuits of totalizing relays T and BT are shown near the bottom of Fig. 6. These relays have operating coils of relatively low resistance which are connected to a number of parallel branch circuits, each including a weighting resistor ATRD, 3TRD, etc., and contacts- 4DR5, 3DR5, etc., of the corresponding floor relays 4BR, 3DR, etc. The contacts 4DR5, 3DR5, etc., are different from the remaining contacts, are held closed by individual holding coils, upon operation of the main relay operating coil, and remain closed after the relay is deenergized, until the circuit of the holding coil is interrupted open. The holding coils for the contacts 4DR5, etc., are shown just above the circuits of relays T and ET, in Fig. 6. The holding coils 4DRH, 3DRI-I, etc., for car A are controlled by a limit switch LSI-I which is opened by suitable cams (not shown) at the upper and lower limits of travel of car A. The holding coils of car B are similar 1y controlled by a limit switch BLSH which opens at both limits of travel of car B.

Various auxiliaries which would be provided in a practical embodiment of the invention, but which have no direct bearing on the novel features of the system, have been omitted in order to simplify the disclosure. For example, some form of annunciator would be provided in both cars A and B for notifying the operator when up or down calls are registered by means of the hall buttons,

Description of operation For convenience in the following description, the various relays and switches individual to car A and those common to all cars of the bank are identified as follows:

Individual to car A.

UUp reversing switch D-Down reversing switch V--Speed switch ESlowdown inductor switch F-Stopping inductor switch M-Auxiliary control relay G-Holding relay H--Stopping relay PIC-Auxiliary stopping relay MSUUp master switch contacts MSD-Down master switch contacts PB-Dispatchers button Q-Quota relay SSelecting relay TTotalizing relay Up car position relays Down car position relays Up call storing relays Down call storing relays Common to all cars:

Up hall buttons Down common selectivity relays Operating sequence In order to illustrate the novel features of operation of the present system, the following operating sequence will be described in connection with the apparatus shown: With both cars standing at the first fioor, car A having arrived there first, it will be assumed that a prospective passenger at the fifth fioor presses the fifth fioor hall button, thereby registering a down call for the fifth floor; that car A is started upward, arrives at the fifth fioor and stops; that down calls are then registered at the second and third floors; that car A is started downward, arrives at the third fioor and stops; that car A is delayed indefinitely at the third floor; that a down call for the fourth fioor is subsequently registered; that car B starts upward from the lower terminal, arrives at the fourth fioor, stops and is started downward; and that car B passes car A at the third fioor, and stops at the second fioor answering the second fioor call previously assigned to car A.

Referring to Fig. 4, as car A is standing at the first fioor, having arrived from the downward direction, the brush 1) of the corresponding fioor selector mechanism is in contact with the segment lb, thereby completing a circuit for the up position relay IUP of car A. A similar circuit is completed by means of the brush Bb of the car B, and the position relays IUP and BIUP are, accordingly, closed.

Referring to Fig. 5, the contacts IUPG of car position relay IUP have completed a circuit for the selecting relay S, which may be traced as follows:

Ll; ISRU; IUPG; PBR; S; Q4; L2.

In response to completion of this circuit the selecting relay S is closed. A similar circuit for relay BS has been completed, by means of the contacts BIUPG of the up position relay BIUP of car B, but, inasmuch as the position relay IUP closed first, the voltage initially applied to the operating coil of the selecting relay BS was insufiiclent to cause closure of the relay. The selecting relay S is, accordingly, closed, Whereas the corresponding selecting relay BS of the car B is open. As shown in the upper part of Fig. 5, the contacts S2 of the selecting relay S being closed, a circuit is completed for the common zoning relay IUX for both cars. This circuit may be traced as follows:

Ll; S2; Q3; IUPS; IUX; L2.

The common zoning relay [UK is, accordingly closed.

R g stration of hall call The prospective passenger at the fifth floor presses the hall button 5D (Fig. 3), thereby p ng a circuit for the operating coil of the fioor relay 5DC, which circuit will be obviousfrom the diagram. In response to completion of. this circuit, the fioor relay 5DC closes, completing a holding circuit for itself by means of its contacts 5DC2; completing a circuit for the call. storing relay 5DR, (Fig. 4) by means of its contacts 5DC3; and closing its contacts 5DC4 (Fig. 4) in the circuit of the call storing relay BSDR. Inasmuch as the selecting relay BS is open, its open contacts BSI prevent closure of the call storing relay B5DR, and the closure of the contacts 5DC4 has no off set at this time, T G1 ing circuit for the call storing relay EDR (Fig. 4) may be traced as follows:

In response to completion of this circuit, the call storing relay 5DR closes, completing a circuit for the hall lantern 5DL, located above the door for car A at the fifth fioor; establishing a holding circuit for itself by means of its contacts 5DR2; and completing a circuit for the selectivity relay EDK (Fig. 6) for the corresponding floor.

The circuit for the floor lantern 5DL, completed upon closure of call storing relay 5DR, is shown near the bottom of Fig. 5, and may be traced as follows:

LI; SDL; 5DR3; L2.

The circuit for the common selectivity relay 5DK may be traced as follows (Fig. 6)

Ll; IURA; IUK; L2.

In response to completion of its closing circuit, traced above, the common selectivity relay SDK closes. The selectivity relay 5DK, in closing, opens the circuit of the call storing relay BSDR by means of its back contacts 5DK2, thereby preventing closure of the call storing relay Bz'aDI-t for car B; and also opens its contacts SDKI in the closing circuit of the call storing relay SDR. As the call storing relay 5DR has closed and established a holding circuit for itself independent of the contacts 5DKI, the opening of the latter contacts has no effect.

Starting of car As the operator of car A has received a start signal on the car annunciator (not shown), he moves the handle of the car switch MS in a direction to cause the car to start upward, and as soon as the car starts, returns the car switch handle to its central position. In response to movement of the car switch handle, a circuit is completed for the up reversing switch U and the auxiliary control relay M. The latter two switches, accordingly, close.

The up reversing switch U, in closing, establishes a circuit for the release coil of the brake M by means of its contacts UI; completes an energizing circuit for the generator shunt field winding l3 by means of its contacts U2, U3; establishes a holding circuit for itself by means of its contacts U4; and completes a circuit for the speed switch V by means of its contacts U5.

The auxiliary control relay M, in closing, opens its contacts M2 (Fig. 2) in the circuit of the fioor relay cancellation coils SDCN, etc., and partly completes circuits for the holding relay G and the inductor switches E, F (Fig. 2) by means of its contacts Ml.

As the brake I4 is now released, and the separately excited field winding 43 of the generator II is energized, the motor I!) starts, and car A is moved in the upward direction. The closure of the speed switch V increases the voltage im pressed on the generator field winding l3, and the motor l0 gradually accelerates to full speed.

Operation at full speed As car A starts upward from the first floor, the carriage 22 of the fioor selector 20 (Fig. 1) partially rotates, thereby causing the brush b to disengage its cooperating row of segments, and causing engagement of brush a with its row of cooperating segments. 

